Cows don’t fart nearly as much I thought they did. But their contribution to air pollution is worse than I imagined.

That’s part of what I learned from “Drawdown,” a new book listing 100 ways to fight global warming.

Compiled by Project Drawdown, a nonprofit organization of scientists, engineers and others, the book ranks the 80 best ideas that can be implemented right now. It lists another 20 that look good but require future breakthroughs, such as the Hyperloop, fusion power and “enhanced weathering of minerals.”

Among the immediately practical steps, eating more plants and less meat — especially beef — ranks as No. 4.

“If cattle were their own nation, they would be the world’s third-largest emitter of greenhouse gases.” The worst gas they emit is methane, which has a greater greenhouse impact than carbon dioxide. A byproduct of the ruminant digestive system, methane is “expelled from both ends of the animal — 90 percent through burps.”

Each of the 100 ideas gets its own brief chapter. There’s a lot of technical detail crammed in, but the book’s organization lends itself to skipping around, and it is lavishly illustrated with gorgeous photos to ward off mental fatigue.

Many of the ideas are about energy, such as wind farms on land (No. 2) or offshore (No. 22) and various forms of solar energy (Nos. 8, 10, 25 and 41). The sections on transportation urge greater use of mass transit (No. 37) and high-speed rail (No. 66), two fields in which Japan excels — and in which it is striving to export its know-how.

Among such familiar ideas, you’ll surely encounter some that are new to you. For me, that included biochar (No. 72), a technique by which ancient Amazonian people turned waste into a charcoal-like substance they buried to enrich the soil, little realizing they were sequestering carbon at the same time.

A few of the ideas are puzzling at first glance. Equipping your home with water-saving devices (No. 46) sounds like a nice idea — but water doesn’t emit greenhouse gases, does it? Maybe not, but the energy that goes into pumping, purifying and heating it does, so saving water helps the atmosphere as well as your utility bills.

Gender equality is another thing that, while obviously good in its own right, has a surprising impact on global warming. Educating girls through secondary school (No. 6) puts the brakes on world population growth, and thus on resource consumption, while recognizing the right of women to own property (No. 62) leads to better management of small farms.

The authors give only qualified recommendations to some things that could have negative side effects, such as incinerating garbage to generate electricity (No. 68), but most of their ideas are “no-regrets” solutions. For instance, walkable cities (No. 54) appeal equally to “environmentalists … economists and epidemiologists.”

What’s No. 1? Proper handling of refrigerants, especially when disposing of old air conditioners and refrigerators. Refrigerant gases are even worse than methane in greenhouse terms, and as the world warms up, their greater use is ironically inevitable.